1. Field of the Invention
The invention generally relates to IP address negotiations, and more particularly, to an apparatus, method, and system to avoid timeouts during IP address negotiations.
2. Description of the Related Art
With growing demand for ubiquitous computing and networking, the Global System for Mobile communications (GSM) system which mainly supports circuit-switched services is not longer a satisfactory option for wireless communications. Telecommunication standard groups therefore, has established standards for third generation (3G) wireless communications technologies, such as the Wideband Code Division Multiple Access (W-CDMA) for the Universal Mobile Telecommunications System (UMTS), Code Division Multiple Access-2000 (CDMA-2000), and Time Division-Synchronous Code Division Multiple Access (TDS-CDMA). 3G wireless communications technologies have been developed based upon Code Division Multiple Access (CDMA) technology. CDMA is a digital radio-frequency (RF) channelization technique defined in the Telecommunications Industry Association/Electronics Industries Association Interim Standard-95 (TIA/EIA IS-95). Wireless communications systems employing the CDMA technology assign a unique code to communication signals and spread these communication signals across a common (wideband) spread spectrum bandwidth. As long as the receiving apparatus in a CDMA system has the correct code, it can successfully detect and select its communication signal from the other signals concurrently transmitted over the same bandwidth. The use of the CDMA technology produces an increase in system traffic capacity, improves overall call quality and noise reduction, and provides a reliable transport mechanism for data service traffic. Thus, 3G wireless communications technologies are directed towards increased data rates, which support large user numbers and data-intensive applications.
In a typical telecommunications environment, a user may use a mobile terminal (MT) that supports any of the 3G wireless communications technologies for ubiquitous computing and networking. An MT generally refers to a portable user equipment, such as a cell phone, a personal digital assistant (PDA), or a smart phone. However, other type of devices may be incorporated with an MT to provide various controls and/or management over the wireless communications networks. A well-known scenario is to incorporate a terminal equipment (TE) with an MT to obtain the wireless communications services via the MT. The TE may be a Personal Computer (PC), a laptop, or a palmtop computer. FIG. 1 illustrates a wireless communications system of such scenario. A system 100 allows a TE 110 to communicate with a service network 130 via an MT 120. The service network 130 can provide wireless connectivity of at least one of the circuit-switched and packet-switched services to the MT 120. In addition, the service network 130 may be connected to other networks, such as the Public Switched Telephone Network (PSTN) or wireline/wireless packet data networks, via a Gi interface. The communications interface between the MT 120 and the service network 130 is a wireless interface Um, and the TE 110 is electronically coupled to the MT 120 via an R interface. The R interface may be a Universal Asynchronous Receiver/Transmitter (UART), a Universal Serial Bus (USB), Bluetooth, or others. The communication over the R interface may employ a Point-to-Point Protocol (PPP), which is a commonly used data link protocol for establishing a direct connection between two networking nodes and is widely supported in numerous operating systems. PPP at the TE 110 and the MT 120 comply with the following specifications: IETF STD 51 (RFC 1661, RFC 1662), RFC 1570, RFC 1989, RFC 1332 for IPv4, and optionally RFC 2472 for IPv6. Alternatively, the TE 110 and the MT 120 may be integrated into a single unit or device.
In system 100, when requiring the packet domain access to the Internet, the TE 110 may use PPP to connect to the service network 130 via the MT 120 and obtain an IP address and some Domain Name Server (DNS) addresses (two addresses in typical). FIG. 2 shows a message sequence chart depicting Internet Protocol Control Protocol (IPCP) negotiations in a wireless communications system using the General Packet Radio Service/Universal Mobile Telecommunications System (GPRS/UMTS) based technology. To begin with, a Link Control Protocol (LCP) negotiation is performed between the TE 110 and the MT 120 to set the configuration of the interfaces at each end, such as setting a datagram size, escaped characters, and magic numbers, and for selecting an authentication protocol, such as Challenge-Handshake Authentication Protocol (CHAP), Password Authentication Protocol (PAP), or ‘none’ (step S210). The MT 120 may negotiate for a CHAP as a first priority. Subsequently, if necessary, the selected authentication algorithm is performed between the TE 110 and the MT 120 (step S220). During the authentication, the TE 110 authenticates itself towards the MT 120 by means of the selected authentication protocol. The MT 120 stores the necessary authentication data and sends a forced positive acknowledgement of the authentication to the TE 110. If ‘none’ is selected as the authentication protocol, no authentication is performed subsequent to the LCP negotiation. After a successful authentication, the TE 110 initiates an IPCP Negotiation to request an IP configuration by sending an IPCP CONFIG REQ message to the MT 120 indicating that either a static or a dynamic IP address and DNS addresses are to be allocated (step S230). Upon receiving the IPCP CONFIG REQ message, the MT 120 sends an ACTIVATE PDP CONTEXT REQ message to the service network 130, including the protocol configuration options (step S240). Accordingly, the service network 130 determines whether to accept the request based on the protocol configuration options in the ACTIVATE PDP CONTEXT REQ message. If the request is accepted, the service network 130 sends an ACTIVATE PDP CONTEXT ACC message, including the allocated IP address and DNS address, to the MT 120 (step S250). Upon receiving the ACTIVATE PDP CONTEXT ACC message, the MT 120 includes the allocated IP address and DNS address in an IPCP CONFIG NACK message, and sends the IPCP CONFIG NACK message to the TE 110 (step S260). Upon receiving the IPCP CONFIG NACK message, the TE 110 sends another IPCP CONFIG REQ message to the MT 120 including the allocated IP address and DNS address (step S270). At last, the MT 120 replies with an IPCP CONFIG ACK message to the TE 110 to confirm the IPCP CONFIG REQ message (step S280). Thus, the link from the TE 110 to the external ISP/Intranet is established and IP packets may be exchanged.
However, there are situations that the consummation of the IPCP Negotiation may be obstructed due to operational delays. For example, the transceiving rate between the MT 120 and the service network 130 may be slower than that between the TE 110 and the MT 120. Thus, the IP address request from the TE 110 may not be granted or may expire because the MT 120 has not completed the address negotiations on the Um interface to render an IP address from the service network 130. Another example of an operational delay occurs when the service network 130 has to get the IP address from some other entity before it can pass the IP address to the MT 120. In doing so, there may be several seconds of delay before the MT 120 receives the IP address. Although the TE 110 is capable of waiting for the MT 120 to eventually render an IP address from the service network 130, there may be an implementation-specific timer for the TE 110. As shown in FIG. 3, if the MT 120 has not replied with an IPCP CONFIG ACK message before a timeout occurs (or the timer expires), the TE 110 may resend the IPCP CONFIG REQ message to the MT 120 (step S310 and S320). The resending of the IPCP CONFIG REQ message may be repeated as many times as configured until an IPCP CONFIG ACK message is received by the TE 110. After a waiting time limit of 12 seconds, for example, has been reached, the resent IPCP CONFIG REQ message would no longer include the request for DNS addresses (step S330). It is noted that, in other operating systems or configurations, the waiting time limit may be longer or shorter than 12 seconds. Next, when receiving an ACTIVATE PDP CONTEXT ACC message after the waiting time limit, the MT 120 would send an IPCP CONFIG NACK message, including only the IP address, to the TE 110 (step S340). Without a DNS address, the TE 110 can not use DNS services. As DNS services are one of the major services on the Internet, the delay may cause increased unsuccessful rate for establishing access connections between the TE 110 and DNS service providers. It is required to provide methods, systems or apparatuses to tolerate the delay during IPCP Negotiations to increase the successful rate of connection establishment.